1. Field of the Invention
The present invention relates generally to a system for filling containers adapted to maintain a gas tight seal. More specifically the present invention relates to an automated system for placing a given product in a sealable package while reducing or substantially eliminating contaimination to the sealing surface of said package caused during the filing or loading operation.
2. Description of the Prior Art
The increasing popularity of perishable food products is largely a result of advances made in the development of systems for containment and storage of such products for purposes of transportation and subsequent presentation to the consumer. Containment and storage systems have allowed the ready transportation of even highly perishable foods over great distances. Moreover, such systems have served to substantially impede product contamination and spoilage of food products and other products sensitive to contamination. Automatic or semi-automatic containment systems have also enabled the cost of many products to remain at a relatively low level while simultaneously enabling a high production output of such products in a containerized form.
The most commonly known containment system is accomplished by sealing the product in a metallic can whereby a metallic lid is crimped thereon to establish an airtight seal. In a canned system, the perishable product is preserved in a palatable state via the introduction of a number of preservatives such as nitrates or the like. Such systems are easily adapted to automatic and mechanized loading processes. Moreover, such canning systems are relatively unaffected by contamination of the sealing edge of the container prior to the placement of the top and subsequent crimping. Disadvantages of canned systems reside in the overall taste and appearance of the food product. Such products are not fresh in the technical sense and are therefore often not preferred in relation to fresh produce or meat products.
Alternatives to canned products exist in the form of frozen food products. In most forms of frozen food products, food stuffs are introduced into a container whereupon a lid is sealed over the food stuffs and the entire container subjected to below freezing temperatures. Frozen food packaging offers the advantage of a diminished need for food preservatives. Additionally, frozen food products offer an advantage from the standpoint of sealing the container itself, since contaminants introduced on the sealing surface ordinarily do not flourish in a low temperature environment. Disadvantages of frozen food products reside in the lack of the fresh food state of the end product. Moreover, many foods, especially poultry and vegetable products, tend to loose flavor and appearance as a result of the freezing process.
The foregoing containment techniques have been superseded in recent years by the introduction of systems adapted to contain a fresh food product in a vacuum or modified gas atmosphere. Such systems ordinarily consist of a tray on which is mounted a plastic lid or wrapper. This lid or wrapper must be sealed securely to the bottom tray in a fashion such as to establish an airtight fit. In an ordinary case, such an airtight seal is accomplished via the use of a bottom tray having a flat lip or flange over which may be placed the lid or alternatively a plastic film.
Disadvantages of such techniques have heretofore resided in the lack of an ability to maintain a gas tight seal between the top and the lid of the container. Such problems are usually caused by contamination of the sealing surface of the bottom tray. Contamination usually occurs during the filling procedure.
Contamination of the sealing surface does not allow a gas tight seal to be created in the package. In this respect, it has been estimated that fresh food containers utilizing such filling systems have on the average experienced almost a 15% contamination rate. As might be expected, this contamination has resulted in reduced customer confidence in the packaging, increased instances of spoilage, and increased costs due to the need to manually examine each seal.